Method and apparatus for diagnosis of liquid losses in pressure measuring transducers filled with pressure transmitting liquids

A pressure measuring transducer comprising:

• a pressure measuring chamber;
• a pressure sensor arranged in said pressure measuring chamber;
• pressure transfer means connected to said pressure measuring chamber, which is sealed against external surroundings by a separating diaphragm, and on which a pressure to be measured acts externally in a measurement operation;
• a sealed inner space, which includes the inner spaces of said pressure transfer means and said pressure measuring chamber, which is filled with a pressure transmitting liquid, and which serves in measurement operations, for transferring a pressure acting on said separating diaphragm to said pressure sensor;
• and
• an apparatus for diagnosis of liquid losses, which includes, arranged in said sealed inner space, a test element, whose outer volume located in said sealed inner space is reducible for diagnosis of liquid losses, and an evaluating unit, which serves during diagnosis for registering a pressure measured by said pressure sensor as a function of volume reduction of said test element, and, on the basis of pressure measured as a function of volume reduction, detects whether liquid has escaped.

A method for diagnosis of liquid losses of a pressure measuring transducer including:

• a pressure measuring chamber;
• a pressure sensor means;
• an apparatus for diagnosis of liquid losses including a test element;
• and an evaluation unit, the method, comprising the steps of:
• reducing the volume of the test element, until either a non-linear falling off of the measured pressure occurs, or until an upper limit for volume reduction is reached;
• upon occurrence of a non-linear decrease, a volume reduction associated therewith is compared with a reference value recorded in the case of intact pressure measuring transducer, and
• on occasion, occurring liquid loss is quantified on the basis of a difference between the associated volume reduction and the reference value.